Non-invasive cardiac monitor and methods of using continuously recorded cardiac data

ABSTRACT

Embodiments of the invention provide methods of obtaining continuous cardiac information from a mammal. First, attach a self-contained, wearable, portable continuous cardiac monitor to the mammal to create a chamber containing electrodes used to detect cardiac signals from the mammal. Next, continuously detect without analyzing the cardiac signals from the mammal for at least 24 hours. Next, store information related to substantially all detected cardiac signals in the cardiac monitor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/765,467 filed Feb. 6, 2006, titled, “Non-Invasive Cardiac RhythmMonitor” and U.S. Provisional Application No. 60/786,502 filed Mar. 29,2006, titled, “Non-Invasive Rhythm Monitor Business Process” each ofwhich is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Abnormal heart rhythms, or arrhythmias, may cause various types ofsymptoms, such as loss of-consciousness, palpitations, dizziness, oreven death. An arrhythmia that causes symptoms such as these is usuallya marker of significant underlying heart disease in the conductionsystem. It is important to make the diagnosis that these symptoms aredue to an abnormal heart rhythm since treatment with various procedures,such as pacemaker implantation or percutaneous catheter ablation, cansuccessfully ameliorate these problems and prevent significant morbidityand mortality.

Since these symptoms can often be due to other, less serious causes, akey challenge is to determine when any of these symptoms are due to anarrhythmia. Oftentimes, arrhythmias occur infrequently and/orepisodically making rapid and reliable diagnosis difficult. Currently,cardiac rhythm monitoring is primarily accomplished through the use ofdevices utilizing short-duration (<1 day) electrodes affixed to thechest. Wires connect the electrodes to a recording device, usually wornon a belt or at the waist. The electrodes need daily changing and thewires are cumbersome. The devices also have limited memory and recordingtime. Wearing the device interferes with patient movement and oftenprecludes performing certain activities while being monitored, such asbathing. All of these limitations severely hinder the diagnosticusefulness of the device, the compliance of patients using the deviceand the likelihood of capturing all important information. Lack ofcompliance and the shortcomings of the devices often lead to the needfor additional devices, follow-on monitoring or other tests to make acorrect diagnosis.

Current methods to correlate symptoms with the occurrence ofarrhythmias, including the use of cardiac rhythm monitoring devices suchas Holter monitors and cardiac event recorders, are often not sufficientto allow an accurate diagnosis to be made. In fact, Holter monitors havebeen shown to not lead to a diagnosis up to 90% of the time (“Assessmentof the Diagnostic Value of 24-Hour Ambulatory ElectrocariographicMonitoring”, by DE Ward et al. Biotelemetry Patient Monitoring, vol. 7,published in 1980).

Additionally, the medical treatment process to actually obtain a cardiacrhythm monitoring device and initiate monitoring is very complicated asillustrated in FIGS. 1 and 2. As is made clear by reviewing FIGS. 1 and2, there are numerous steps involved in ordering, tracking, monitoring,retrieving, and analyzing the data from the device. In most cases, thepatient must go to a separate office or facility to obtain the cardiacrhythm monitoring device. The difficulty posed by these factors leads tofewer patients receiving cardiac rhythm monitoring since physicians maybe reluctant to go through the paperwork and burden required to initiatemonitoring for a potentially lower-risk patient who presents with mildsymptoms.

Once monitoring has been initiated, a large component of the processtoday involves a 3rd party cardiac rhythm monitoring company which iscontacted, either by the patient or directly by the device, whensymptoms or certain parameters set in the device are met. The screeningalgorithms used by devices to automatically determine if certainparameters have been met are usually simple and not very specific sincethe ability to process complex electrocardiogram (ECG) data is notpossible in these devices due to size, cost, and a limited ability andunderstanding of how to process ECG signals accurately. The 3rd partymonitoring company will then retrieve the data from the device over thetelephone or wirelessly from the device, and will contact the patient'sphysician if particular parameters are met. Though this step can beuseful in some instances, for the vast majority of patients it isunnecessary and only results in a physician being needlessly contacted,often in the late hours of the night. It is extremely rare for thephysician to recommend that the patient go to the hospital or emergencyroom to be treated at the time the physician was notified.

Further, the majority of devices used today are ordered by acardiologist or a cardiac electrophysiologist (EP), rather than thepatient's primary care physician (PCP). This is of significance sincethe PCP is often the first physician to see the patient and make theconnection that the patient's symptoms could be due to an arrhythmia.After the patient sees the PCP, the PCP will make an appointment for thepatient to see a cardiologist or an EP. This appointment is usuallyseveral weeks from the initial visit with the PCP, which in itself leadsto a delay in making a potential diagnosis as well as increases thelikelihood that an arrhythmia episode will occur and go undiagnosed.When the patient finally sees the cardiologist or EP, a cardiac rhythmmonitoring device will usually be ordered. The monitoring period canlast 24-48 hours (Holter monitor) or up to a month (cardiac eventmonitor). Once the monitoring has been completed, the patient mustreturn the device, which itself can be a hassle for the patient. Afterthe data has been processed by the monitoring company or by a technicianon-site at a hospital or office, a report will finally be sent to thecardiologist or EP for analysis.

In view of the shortcomings in cardiac rhythm monitoring and theprocesses to utilize data collected by cardiac rhythm monitoringsystems, there is a need for improved non-invasive cardiac monitoringdevices and methods.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, there is provided a heartmonitor having a housing; a surface on the housing adapted to besealably engaged to a mammal; an adhesive on the surface that is adaptedto remain affixed to the mammal for at least 7 days. There are at leasttwo electrodes positioned to detect an ECG of the mammal while thesurface is sealably engaged to the mammal; an electronic memory withinthe self contained and sealed housing; and wiring within the selfcontained and sealed housing connecting the electronic memory to theelectrodes; wherein, the electronic memory is sized to store at least 24hours of continuous ECG information. In one aspect, the same at leasttwo electrodes are used to detect an ECG of the mammal for as long asthe adhesive remains affixed to the mammal. In another aspect, theadhesive is adapted to remain affixed to the mammal for at least 7 dayswithout skin irritation. In another aspect, the adhesive is adapted toremain affixed to the mammal for at least 2 weeks or for at least 4weeks. In another aspect, the wiring is entirely within the selfcontained and sealed housing. In another alternative embodiment, thereis provided a rim extending from the surface on the housing. In onealternative, a portion of each of the least two electrodes is within aportion of the surface bounded by the rim. In another aspect, theelectronic memory, the wiring and the electrodes are a single, hardwired unit. In another aspect, when the adhesive is affixed to themammal, a watertight chamber forms around the at least two electrodes.In another alternative, when the adhesive is affixed to the mammal, therim forms a watertight chamber around the at least two electrodes. Inone aspect, the surface has a tapered thickness and extends beyond theportion of the housing containing the plurality of electrodes. Inanother aspect, the adhesive on the surface that is adapted to remainaffixed to the mammal for at least 7 days is a pressure sensitiveadhesive selected from the group consisting of: polyacrylates,polyisobutylenes, and polysiloxanes. In another alternative embodiment,the housing is made of a flexible bio compatible polymer that provides awatertight enclosure for the electronic memory and wiring.

In yet another alternative, the watertight chamber comprises separatewatertight enclosures around each electrode of the at least twoelectrodes. In another aspect, there is provided a port forelectronically accessing the electronic memory and a seal is provided onthe port. The seal may be formed by the housing. In another aspect,there is provided an activation or event notation button or switchformed in the housing that is accessible while the adhesive is affixedto the mammal. In one aspect, actuation of an activation or eventnotation button or switch increases the fidelity of the ECG informationstored in the electronic memory. In another aspect, an indication ofactivation or event notation button or switch activation is stored inthe electronic memory with contemporaneous ECG information. In yetanother alternative there is provided an indicator that activates whenECG of the mammal is being detected. In another aspect, an indicator isprovided that provides a continuous indication as long as ECG of themammal is detected. In another aspect, an indicator is provided thatactivates when a monitoring period is completed. In another alternative,at least a portion of the housing is colored to match the skin tone ofthe mammal, or contain a decoration, art work, design, illustration orcartoon character to provide a custom appearance to the device.

Another embodiment of the present invention provides a cardiac monitorhaving a housing; a plurality of electrodes within and extending fromthe housing; a state machine within the housing configured todigitialize and store in memory signals from the plurality ofelectrodes; a sealing surface and an adhesive on the sealing surfaceconfigured to form a watertight perimeter around the plurality ofelectrodes when the housing is affixed to a mammal. In one aspect, theportion of each of the plurality of electrodes that is in contact withthe mammal has a rounded surface. In another aspect, the sealing surfacecomprises a lip having a tapered thickness. In another aspect, thethinnest portion of the sealing surface is in the outer perimeter of thesealing surface. In another aspect, the thickness of the outer perimeterof the sealing surface is less than about 2 mm. In another aspect, thesealing surface is affixed to the mammal each electrode of the pluralityof electrodes is contained within a separate watertight chamber. Inanother aspect, the sealing surface comprises a rim extending from theself contained and sealed housing. In another aspect, when the sealingsurface is affixed to the mammal each electrode of the plurality ofelectrodes is contained within a separate watertight chamber. In anotheraspect, the adhesive on the sealing surface is a pressure sensitiveadhesive suited to long term cardiac monitoring. In another aspect, theadhesive on the sealing surface is a pressure sensitive adhesiveselected from the group consisting of: polyacrylates, polyisobutylenes,and polysiloxanes. In another aspect, the state machine within thehousing is further configured to offload data stored in memory. Inanother aspect, the housing is made of a flexible biocompatible polymerthat provides a watertight enclosure for the state machine.

In another alternative embodiment, there is provided a method ofobtaining ECG information from a mammal by attaching a self-contained,wearable, portable ECG monitor to the mammal to create a chambercontaining electrodes used to detect ECG signals from the mammal; acontinuously detecting without analyzing the ECG signals from the mammalfor at least 24 hours; and storing information related to substantiallyall detected ECG signals in the ECG monitor. In one aspect, theself-contained, wearable, portable ECG monitor includes: a plurality ofelectrodes, a power source and memory contained within a watertighthousing. In another aspect, the attaching step comprises placing theelectrodes on the mammal and sealing the electrodes between the housingand the mammal using an adhesive on a rim of the housing that surroundsthe electrodes. In yet another aspect, there is provided a mammalperceivable indication that the ECG monitor is operating. In anotheraspect, the providing step is performed after the attaching step. Inanother aspect, the providing step is performed after the storing step.

In another aspect, the providing step is continuously performed duringthe continuously detecting step. In another aspect, there is provided anindication that the ECG monitor is operating after the attaching step.In another aspect, there is a step of retrieving stored informationrelated to substantially all detected ECG signals from the monitor andanalyzing the retrieved information to identify ECG events. In oneaspect, the analyzing step is performed after the ECG monitor is removedfrom the mammal. In another aspect, removing the ECG monitor from themammal before the retrieving step. In another aspect, the detecting andstoring steps are performed without identifying ECG events in theinformation related to substantially all detected ECG signals. In yetanother aspect, the detecting and storing steps are performed withouttransferring information between the housing and a device not attachedto the mammal. In another aspect, the detecting and storing steps areperformed without transferring information between the housing and adevice not contained within the housing. In another aspect, processinginformation from the storing step to determine the presence of anarrhythmia. In another alternative, processing information from thestoring step is performed using more than one algorithm to determine thepresence of an arrhythmia. In another alternative, processinginformation from the storing step to evaluate the presence of anarrhythmia is performed during a selected time interval. In one aspect,the information from the storing step is processed during the sameselected time interval on more than one day. In another aspect,processing information from the storing step to evaluate the presence ofan arrhythmia is performed during a time interval indicated by themammal.

In another embodiment, there is a method of analyzing ECG informationthat includes collecting a plurality of self-contained, wearable,portable ECG monitors each of the ECG monitors electronically storing atleast 24 hours of continuously detected and unanalyzed ECG signals froma mammal; retrieving ECG information stored in each of the plurality ofself-contained portable ECG monitors; and forwarding retrieved ECGinformation. In one aspect, there is the: step of sending the collectedself-contained portable ECG monitors to a processing center before theretrieving step. In another aspect, the forwarding step includeselectronically sending retrieved ECG information to a processing center.In another aspect, the method includes removing a self containedportable ECG monitor from a mammal before the collecting step. In yetanother aspect, there is a step of analyzing the retrieved ECGinformation to identify ECG events or parameters. In one aspect, theanalyzing step is done after the forwarding step. In another aspect, themammal specific information in at least one of the plurality ofself-contained, wearable, portable ECG monitors includes substantiallyall of the ECG information from a mammal for at least 7 days. In anotheraspect, the ECG information in the forwarding step includessubstantially all of the ECG information from a mammal for at least 7days. In another aspect, the forwarding step includes providing mammalspecific ECG information to a physician identified in the collectingstep. In another aspect, processing information from the forwarding stepto determine the presence of an arrhythmia. In another aspect,processing information from the forwarding step is performed using morethan one algorithm to determine the presence of an arrhythmia. In stillanother aspect, processing information from the forwarding step toevaluate the presence of an arrhythmia is performed during a selectedtime interval. In another aspect, the information from the forwardingstep is processed during the same selected time interval on more thanone day. In another alternative, processing information from theforwarding step to evaluate the presence of an arrhythmia is performedduring a time interval indicated by the mammal. In another aspect,processing information from the forwarding step is analyzed to determinethe presence of an arrhythmia. In another aspect, the method provides auser access to information from the retrieving step or the forwardingstep so that the user may process the provided information using morethan one algorithm to determine the presence of an arrhythmia. Inanother aspect, the method provides a user access to information fromthe retrieving step or the forwarding step so that the user may processthe provided information to evaluate the presence of an arrhythmiaduring a selected time interval. In another aspect, the providedinformation is processed during the same selected time interval on morethan one day. In another aspect, the method provides a user access toinformation from the retrieving step or the forwarding step so that theuser may process the provided information to evaluate the presence of anarrhythmia during a time interval indicated by the mammal.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 is a flow chart illustrating a prior art method of cardiacmonitoring;

FIG. 2 is a flow chart representing a prior art method of cardiacmonitoring;

FIG. 3A is a top down view of an embodiment of a continuous cardiacmonitor;

FIG. 3B illustrates the cardiac monitor of FIG. 3A affixed to the chest;

FIG. 4 the basic layout of components in a continuous cardiac monitor;

FIG. 5 is a schematic diagram of an action sequencer embodiment;

FIGS. 5A and 5B illustrate, respectively, exemplary memory read andretrieval steps;

FIGS. 6A-6D illustrate various views of continuous cardiac monitorembodiments having a single electrode pocket;

FIGS. 7 A-7D illustrate various views of continuous cardiac monitorembodiments having dedicated electrode pockets;

FIGS. 8A-8C illustrate various views of another continuous cardiacmonitor embodiment;

FIG. 9 illustrates the monitor of FIGS. 8A-C in place on a patient;

FIG. 10 illustrates another continuous cardiac monitor embodiment;

FIG. 11 illustrates another continuous cardiac monitor embodiment;

FIG. 12A illustrates another continuous cardiac monitor embodiment andFIG. 12B illustrates the monitor in FIG. 12A in place on the chest;

FIGS. 13A and 13B illustrate various event notation embodiments;

FIG. 14 illustrates another continuous cardiac monitor embodiment;

FIG. 15 illustrates a method of obtaining and evaluating continuouscardiac data;

FIG. 16 illustrates a comprehensive method of treatment optionsavailable based on the use of continuous cardiac monitors;

FIG. 17 illustrates an alternative cardiac data processing method basedon the availability of continuous cardiac data;

FIG. 18 illustrates an method of method of storing continuous cardiacdata;

FIG. 19 illustrates a method of collecting and analyzing data from aplurality of continuous cardiac monitors.

DETAILED DESCRIPTION OF THE INVENTION

In the US, over 2.3 million individuals suffer from arrhythmias, withover 700,000 new cases diagnosed annually. Over 80-90% of thesearrhythmias occur in individuals over 40 due to the association ofarrhythmias with aging and the occurrence of age-related events, such asheart attacks. Additionally, each year over 250,000 people die suddenlyin the US due to arrhythmias (“Heart Disease and Stroke Statistics”,from the American Heart Association published in 2005). Given thesestaggering figures, the diagnosis of arrhythmias is of crucialimportance, especially since many effective treatments exist.

The occurrence of an arrhythmia can cause a range of symptoms frompalpitations, dizziness, shortness-of-breath, and chest pain, toloss-of-consciousness and even death. In some individuals, arrhythmiasmay not lead to perceptible symptoms, even though these individuals maystill be at risk for numerous arrhythmia-related complications such asstrokes. Since many of the symptoms caused by arrhythmias can also becaused by other, less serious conditions, a major challenge forphysicians is determining when these symptoms are actually due to anarrhythmia. This can be difficult because arrhythmias often occurinfrequently and episodically, sometimes only once every few weeks andusually without warning. Additionally, arrhythmias sometimes also onlylast for a few seconds to a few minutes. Given that there are many typesof arrhythmias, it is hard to know what treatment to recommend if anarrhythmia does not occur when a physician is present, Diagnosis is evenmore challenging in the patient who may be asymptomatic, but issuspected of having an arrhythmia

Arrhythmias may be diagnosed using medical equipment, most often withcardiac rhythm monitors. Monitoring techniques used by available cardiacrhythm monitors include monitoring the heart rhythm for a short periodof time or monitoring intermittently. Current standard techniques anddevices for detecting arrhythmias include a resting ECG, which recordsabout 15 seconds of continuous cardiac rhythm activity. Intermittentcardiac rhythm monitors include a Holter monitor that records 24-48hours of cardiac rhythm activity during routine daily activities. Thedata recorded by a Holter monitor is intermittent and not actuallycontinuous because the recorded data stream is interrupted when thepatient is obligated to remove the monitor to bathe or perform otherdaily personal hygiene activities or to replace electrodes daily or atany other time when the electrode/monitor connection is interrupted suchas when the monitor is disconnected during restless sleep. Cardiac eventmonitors are another form of intermittent cardiac rhythm monitor. Acardiac event monitor records cardiac activity from a looping memoryonly when symptoms associated with an arrhythmia are detected by thepatient or by a preprogrammed arrhythmia detection algorithm in themonitor.

These diagnostic methods and tools have significant limitations indiagnosing arrhythmias and assessing the efficacy of treatment of anarrhythmia because of the limited recording time windows and thesubjectivity of the activation of a monitor by a patient. If a patientis asleep and experiences an arrhythmia, then it is unlikely that thepatient will wake up and activate the event monitor. Similarly, if apatient suffers from an arrhythmia outside of the parameters of thepreprogrammed detection circuit, then those arrhythmias will remainundetected as well. More importantly, because these conventionalintermittent cardiac rhythm monitors rely on looping memory, relevantinformation about the cardiac rhythm that are patient-specific oroutside of the parameters of the arrhythmia detection algorithm areusually not recorded. Lack of relevant data or a more robust set ofpatient specific data adversely impacts the usefulness of the dataacquired during a given monitoring period.

It is believed that conventional cardiac rhythm monitoring techniqueshinder the ability to accurately diagnose arrhythmias because of thelack of availability of continuous patient specific data for lateranalysis, comparison and confirmation and the fact that the only dataavailable for later analysis is data that has been subjectively limitedduring the monitoring period. In 1997, 729 consecutive cases wereanalyzed to test the hypothesis that continuous loop cardiac eventmonitors provide useful diagnostic information about common clinicalproblems. The study found cardiac event recorders provided anexplanation of cardiac symptoms in about half the studied cases. Seriousand potentially life threatening arrhythmias (ventricular tachycardia,supraventricular tachyarrhythmias (SVT) including atrial fibrillationand/or flutter or paroxysmal SVT, or high grade bradyarrhythmias) weredetected in only about 25% of the cases. Importantly, the studyconcluded that cardiac event recorders were of little utility inidentifying a probable cause of syncope and had no diagnostic yield inpatients with nonspecific symptoms (“Utility of Patient-ActivatedCardiac Event Recorders in General Clinical Practice”, by PeterZimetbaum et al in The American Journal of Cardiology, vol. 79,published on Feb. 1, 1997). Another study concluded that intermittentand symptom-based monitoring is highly inaccurate for identifyingpatients with any or long-duration atrial fibrillation or atrialtachycardia or for assessing atrial fibrillation or atrial tachycardiaburden (“Comparison of continuous versus intermittent monitoring ofatrial arrhythmias”, by Paul Ziegler et al in Heart Rhythm, vol. 3,published in December 2006). Another 2006 study of the optimal durationof cardiac event recording found that more relevant arrhythmias (i.e.,paroxysmal atrial fibrillation, atrial flutter, atrial tachycardia, SVTnot specified and ventricular tachycardia) and less relevant arrhythmias(i.e., ventricular or atrial premature beats, sinus tachycardia. orbradycardia) were identified during the third week of monitoring ratherthan during the first two weeks of monitoring. The study concluded thata minimum of two weeks of recording appeared necessary (“Optimalduration of event recording for diagnosis of arrhythmias in patientswith palpitations and light-headedness in the general practice”, by EmmyHoefman et al in Family Practice, published Dec. 7, 2006).

Since intermittent cardiac rhythm monitors record only selected momentsduring a monitoring period, there are large time gaps and discontinuityin the recorded data. Because of the gaps in data, time stamps in therecorded data stream are needed. The time stamps in the recorded datastream are needed to distinguish between recorded events. In someintermittent cardiac rhythm monitors, one recording is typically 4 to 5minutes long, with about half that being used to store the time justprior to the onset of an event, and half used to store 2 to 2.5 minutesafterwards. Significantly, what is recorded, and when the recordingbegins, is not decided by a skilled physician but rather by the patientor auto-triggered by an arrhythmia detection algorithm. Moreover, afterthis 5 minute recording, there are often large indeterminate time gaps,hours or even weeks, before the recording of the next 5 minute intervalis triggered by the patient or auto-triggered by an arrhythmia detectionalgorithm. In summary, recorded data streams in intermittent cardiacrhythm monitors consist of small blocks of time stamped ECG dataseparated by large time blocks where no data recordings are collected.

Rather than subjectively limit the data collected by an event monitor,embodiments of the cardiac monitor of the present invention collectsubstantially all cardiac or other physiological data during themonitoring period. Moreover, the monitoring period used by the presentinvention is longer so as to increase the likelihood that the collectedcontinuous data will yield—an accurate diagnosis when later analyzed andevaluated. Data obtained from intermittent cardiac rhythm monitorsnecessarily excludes subjectively normal cardiac data. Subjectivelynormal data is excluded in these systems since the looping memory onlyrecords when the wearer or the monitor's detection algorithm believesthat an abnormal rhythm is present. As a result, other indicia orprecursors of arrhythmia outside the perception of the patient or theparameters of the monitor's arrhythmia algorithm are (1) not evaluated;(2) not recorded and (3) not available for different or moresophisticated analysis or processing.

Under-detection and under-recognition of arrhythmias in patients mayhave significant clinical consequences. If an arrhythmia is not detectedand if it recurs, a patient is exposed to serious morbidity sincearrhythmias can cause loss-of-consciousness, strokes, or heart attacks.In their most serious form, arrhythmias may lead to death. On a morepractical level, the under-detection of an arrhythmia may also lead aphysician caring for a patient to not treat a patient with theappropriate medications and/or procedures, which otherwise could preventfurther arrhythmia episodes. Each of these consequences may bedetermined, evaluated or predicted using vastly different indications,symptoms, or predictors. It is highly unlikely that any singleevaluation, processing or analytical technique—whether manual orautomatic—will successfully determine each of the myriad of differentindications, symptoms, or predictors. Rather than risk misidentifying,mischaracterizing or under-identifying an arrhythmia by choosing apreset algorithm, the continuous, unprocessed data collected byembodiments of the device described herein would provide cardiac datathat may be evaluated using numerous different automatic and/or manualdetection techniques during numerous temporal situations to provide amore robust and complete likelihood of diagnosis.

Rather than attempting to decide whether a rhythm is abnormal in realtime by some predetermined algorithm, the continuous cardiac monitor ofthe invention simply creates a continuously digitized time stream overthe monitoring period. The continuous cardiac monitor data storagediffers from intermittent cardiac rhythm monitoring device data storagein at least at least three ways.

First, the data stored in a continuous cardiac monitor does not have the“off period” or time blanks present in intermittent cardiac rhythmmonitor device data. Because the continuous monitoring electrodes are inconstant skin contact during the monitoring period and the sameelectrodes are used during the entire monitoring period, the inventivedevice is on and always sensing during the monitoring period. UnlikeHolter type monitors where data collection is interrupted for dailyelectrode changes or personal hygiene, the design of continuous cardiacmonitors utilizes the same electrodes for the entire monitoring periodwithin a sealed watertight enclosure that allows monitoring to continueregardless of the performance of personal hygiene or any other activity.Unlike loop or event type intermittent monitors, continuous cardiacmonitors store all data continuously instead of over-writing temporarydata when triggered to store the data. Since all rhythms are recordedduring a monitoring period, there are no time gaps or intentional blankswhere ECG rhythm is excluded from recording.

Second, the data stored in continuous cardiac monitors of the inventionis unfiltered, unaltered, and not subjected to local or on-deviceprocessing. Continuous cardiac monitor data is simply digitized andstored. In summary, the data collected by the inventive continuouscardiac monitors described herein represents a comprehensive andcomplete, uninterrupted recording of a patient's cardiac data during thetime of attachment and throughout the monitoring period. The data is inits natural, biological form and is not filtered by any circuit orsoftware prior to onboard storage. Continuous cardiac monitors of theinvention deliver unprocessed physiological data from the memory,upstream to a report generating computer. The complete, unfiltered datafrom the monitoring period may then be analyzed, processed or evaluatedby a physician or other user who determines the appropriate screening,processing or evaluating algorithm or data analysis method.

In contrast, conventional intermittent cardiac rhythm monitors includehardware and software based capabilities to perform real time analogand/or digital signal processing of the selected subset of monitoreddata. The signal processing of these devices is needed for a variety oftasks, such as to narrow the frequency band, detect the R-wave, measureR-R intervals, and perform a myriad of tests on and around the QRScomplex. The signal processing programs and microprocessor powerrequired for such devices is large given that these devices attempt toprocess real time ECG data to identify ECG abnormalities based on thepre-programmed and predetermined criteria. Importantly, the kind ofprocessing performed in intermittent cardiac rhythm monitors requirestransformation of the data stream. This type of data transformationimpacts what is ultimately recorded in the memory of the intermittentcardiac rhythm monitor. In addition, performing data transformations andtests locally on the device requires a filtering and detecting system,along with extensive software algorithms. However, even though asignificant amount of rhythm data is never recorded, the tests performedin intermittent cardiac rhythm monitors are redundant since theselected, recorded data from these devices is provided upstream to andprocessed by a report generating computer.

Third, the underlying principle that determines which data gets storedand how this data is processed is different. In a continuous cardiacmonitor, all data is stored irrespective of whether or not the datacorresponds to an arrhythmic condition. Data is processed at theconclusion of the monitoring period using virtually any availableprocessing algorithm or technique. If a continuous cardiac monitordevice is recording, it is recording all or substantially all cardiacdata.

Rather than record a continuous, unfiltered, electrical history for themonitoring period, conventional intermittent cardiac rhythm monitorsmake an error prone attempt at recording only the actual arrhythmiaevents based on either patient initiated or algorithmic auto-triggers.Since conventional rhythm monitors only seek to record perceivedarrhythmia events, all other events, including unperceived arrhythmiaevents are excluded from the data. Conventional intermittent cardiacrhythm monitors depend upon a patient and/or an algorithm to choose whatsubset of data from a monitoring period will be stored and available forlater review and diagnosis. As a result, data stored in the memory ofsuch devices has a much different content. Even during recording, thedata may not be all data during that period but rather only a filteredor pre-processed version of the actual data. The data is different fromcontinuous data because of the common practice in prior art intermittentcardiac rhythm monitors to attempt to minimize the amount of data toincrease the number of discrete events that can be recorded. Data isminimized using well known prior art data reduction algorithms, such asturning point algorithms, AZTEC (Amplitude Zone Time Epoch Coding),CORTES (Coordinate Reduction Time Encoding System), the data reductionalgorithms and arrhythmia detection algorithms of Tompkins and Websterof the University of Wisconsin, Madison, and those found in their text,Design of Micro-Computer based Medical Instrumentation (Prentice Hall,1981). Intermittent cardiac rhythm monitors process data concurrent withthe monitoring period using only processing algorithms stored on themonitor in an attempt to record only abnormal events. If an intermittentcardiac rhythm monitoring device is on, it mayor may not be recordingECG data depending upon whether an abnormal event is perceived by thepatient or the on-board algorithm.

Assessing a patient's condition based on an evaluation of continuous,unprocessed, long-term cardiac data made available by the presentinvention has several distinct advantages. A conventional pre-setmonitoring program would likely eliminate data as being outside of thepre-set parameters whereas the eliminated (i.e., not recorded) data mayprove relevant only after later, more robust analysis using a differentalgorithm or processing technique. Since devices of the presentinvention record all physiologic data, a physician, or technician mayprocess or analyze the data using any specific time during a monitoringperiod, any continuous time period during the monitoring period orrepeatably obtaining data from a specific time period at a designatedtime interval. Moreover, because substantially all cardiac data isavailable for the entire monitoring period, the likelihood is increasedthat when potentially contributory events such as particular activitiesor situations are identified, data will be available from thatidentified time period as well as from nearby time periods since thisdata may provide clues as to why the event occurred. Conventionallyrecorded cardiac rhythm data does not provide such robust time basedselectivity because the recorded data contains only the data that neededto be recorded based on pre-set parameters—i.e., the data included whatthe pre-programmed algorithm determined was an abnormal rhythm based onthe specific parameters of that specific device.

Conventional intermittent cardiac rhythm monitors include processorintensive algorithms or methods processed on-chip or on-board theinstrument. The inventive continuous cardiac monitors described hereinare a distinct departure from prior art intermittent cardiac rhythmmonitors such as, for example, the type described in US PatentApplication Publication US 2003/0083559 to Thompson. The Thompsondevice, like other auto-trigger intermittent cardiac rhythm monitors,includes some form of a trigger and/or arrhythmia detector capability todetect and record only suspected abnormal rhythms. As a result, theThompson device, like other auto-trigger intermittent cardiac rhythmmonitors, must process and convert the incoming QRS data stream so thatit may be in a form acceptable to the trigger and/or arrhythmia detectorcircuit(s).

The inventors of the present invention recognized that for mostsituations recorded cardiac monitor data—whether from an intermittent ora continuous cardiac rhythm monitor—is best processed after themonitoring period using more powerful computers and a greater variety ofprocessing algorithms than are available on intermittent cardiac rhythmmonitors. The inventors also recognized that conventional cardiac rhythmmonitors include signal processing that is replicated upstream in moresophisticated systems. Embodiments of the continuous cardiac monitor ofthe present invention are designed contrary to intermittent cardiacrhythm monitors. As a result, instead of attempting to identifyarrhythmias or process the QRS complex, continuous cardiac monitors ofthe invention eliminate this data processing redundancy and insteadcapture and record raw data for later upstream data processing usingappropriate user selected processing. A continuous cardiac monitor is abiological analog signal acquisition and disposition device. Because theoperation of the inventive monitoring device is built around a simpleload-store-forward architecture, storage of signals in these devicesrequires no analog or digital signal processing. As a result, theinventive continuous cardiac monitoring device is constructed using afew common electronic components including a state machine having simplehardwired logic to perform functions related to continuous cardiacmonitoring.

Recognizing that data transformation, filtering, processing, analyzingand algorithm selection are better left to individual users to analyzebased on patient specific criteria after data collection, embodiments ofthe present invention instead record continuously all or substantiallyall of the data during a monitoring period. This fundamental differenceresults in the reduction or complete elimination of hardware andsoftware complexity in continuous cardiac monitors. Digital signalprocessing components and arrhythmia detection algorithms, along withthe micro-computers or microcontrollers needed to run them—so pervasivein intermittent cardiac rhythm monitors—are not needed in continuouscardiac monitors.

FIG. 3A illustrates a top view of an embodiment of a continuous cardiac:monitor 100 according to one embodiment of the present invention. Thecontinuous cardiac monitor 100 includes a housing 152. The housing 152provides a watertight enclosure to encapsulate the electronic componentsof the device. The housing 152 may be formed from any flexible, durablematerial. In one embodiment, the housing is a biocompatible polymer. Inone specific embodiment, the housing is formed from silicone.

The housing 152 has a central portion 133 containing the variouselectronic components used to record continuous physiological signalsfrom a mammal wearing device. In the illustrated embodiment, a flexiblerim or membrane 150 is a part of the housing 152 that extends beyond thefootprint of the electrodes 105 and the central portion 133.

The continuous cardiac monitor 100 includes at least two electrodes 105positioned to detect an ECG of the mammal while the surface is sealablyengaged to the mammal. Contained within the self contained and sealedhousing 152 are conventional electronic components such as analogcircuits 110, digital circuits 115, a battery 125, memory 122 (not shownbut within the digital circuits 115), an activation or event notationbutton or switch 130 and communications port 140 mounted on a flexiblecircuit board 120.

Wiring or other suitable electrical connections within the housing 152connect the electronic memory 122 (not shown but within the digitalcircuits 115) to the electrodes 105. The flexible circuit board orsubstrate 120 may comprise a resilient material upon which several orall of the electronic and electrical components are mounted. Flexiblesubstrate 120 may include an integral or separate interconnect patternof electrical conductors that provide for interconnection between thevarious components disposed on flexible substrate 120. Suitablematerials that may be used to fabricate the flexible substrate 120include Mylar, flexible foil, Kapton, and polymer thick film (PTF).

FIG. 3B illustrates a cardiac monitor 100 on the chest 16 of a male,human. The flexible membrane 150 is clearly shown extending from thecentral electronics portion of the device. The flexible membrane or lip150 includes a surface adapted to be sealably engaged to a mammal. Inone embodiment, there is an adhesive on the surface that is adapted toremain affixed to the mammal for at least 7 days.

As described in greater detail below, the signal detected by theelectrodes 105 is continuously stored in the electronic memory 122contained within the self contained and sealed housing 152.

The adhesives used with embodiments of the present invention areselected for long term adhesion. Long term adhesives refers to adhesivessuited to maintaining a continuous cardiac monitor affixed to a mammalfor the duration of the monitoring period with minimal discomfort forthe mammal undergoing monitoring.

Adhesives typically used for conventional intermittent ECG electrodeattachment are inadequate since these adhesives are generally intendedto keep an electrode in place for only 24 hours, or perhaps 48 hours inan extreme case. Moreover, a gel component that may also act as anadhesive is commonly used in these electrodes which can be caustic tothe skin if used for long-term applications such as those describedherein.

We have found that certain types of adhesives, known aspressure-sensitive adhesives, or PSAs, are suited to our long-termcardiac monitoring applications. In particular, we have identifiedseveral PSA formulations, such as polyacrylates, polyisobutylenes, andpolysiloxanes, suited to our applications. Hydrophilic PSAs of thegeneral polyethylene oxide type, such as those described in U.S. Pat.No. 5,489,624 and U.S. Pat. No. 5,536,768, both to Kantner, et al., aredescribed as being suited to the short term electrode placement typicalof intermittent cardiac monitors. Specifically, Kantner describeshydrophilic polyethylene oxide PSAs used in conjunction with theshort-term electrodes mentioned above and including the causticconductive gel often found in these type of short-term disposableelectrodes. As such, PSAs of this type would not likely be suited tolong term monitoring applications as described herein.

We tested various polyacrylates, polyisobutylenes, and polysiloxanesPSAs on human skin to determine the long-term adhesive capabilities ofthese PSAs. One PSA that worked well was Duro-Tak 387-2287/87-2287—anacrylate-vinylacetate non-curing PSA available from National Starch &Chemical Co. This PSA was used to affix a prototype device similar tothe device illustrated in FIG. 3A to human skin on the chest near theheart as illustrated in FIG. 3B. Our test showed that with this PSAadhesive the device remained attached in the same place on the chestskin for over 3 weeks. The subject wearing the patch performed normaldaily activities such as bathing, showering, exercising, and sleepingwithout impediment from the device. The device was removed at the end ofthe test period without difficulty. An inspection of the skin afterremoval showed no signs of significant skin irritation or necrosis.Thus, it is believed that PSAs such as polyacrylate, polyisobutylene, orpolysiloxane and the like are suited for long-term monitoringapplications coextensive with the available memory on the continuousmonitoring device. As such, long term monitoring devices of the presentinvention enable the collection of continuous long term cardiac data fora clinically relevant time period, thereby increasing the likelihood ofthe detection of arrhythmias. Because the continuous monitoring devicesof the invention have been designed for long term monitoring, physiciansand other health care providers or even individuals would have a devicethat may remain comfortably affixed in a monitoring condition for a widevariety of monitoring durations such one, two, three or four weeks orany number of days up to 30 days.

In addition to selecting a suitable long term adhesive, other aspects ofcontinuous cardiac monitors of the present invention are designed toenhance patient comfort while maintaining the device in position todetect a quality signal. One aspect related to maintaining the device inposition is the type of adhesive and the surface area on the deviceavailable for or dedicated to affixing the device to the skin of themammal. During long-term applications, device/adhesive combination andthe device/skin interface will be exposed to varying moisture, pressure,force, and heat conditions. It is believed that a large ratio ofadhesion surface area (i.e., portion of the device available for or usedto affix the device to the skin) to non-adhesion area (i.e., portion ofthe device not used to affix the device to skin) is useful inmaintaining the device in position. Given that a mammal's body bends andis curved, we have found that by providing an area around the edges ofthe electronics portions of the device to increase the surface areaavailable for adhesion also increases the likelihood that the devicewill remain in place during the monitoring period. Large and taperedrims as described herein dramatically increase the surface areaavailable for adhesion. Moreover, these rims are relatively thin andflexible thereby increasing the likelihood that the device will conformto the body during movement while maintaining an adequate seal to acurved, moving, and bending surface. It is believed that providing a rimor lip to increase the surface area for adhesion is likely to be a keyfactor for long-term device placement.

In some embodiments, the lip is thin and flexible with a thickness thattapers away from the electronics portion of the device. Typically, thecombination of the lip and the adhesive is about 1 mm to about 4 mmthick near the electronic components. The thickness near the electricalcomponents tapers to a thickness of about 0.5 mm to about 2 mm at theoutermost edge. The thin conformal nature of this tapered designdecreases the likelihood that the monitor may inadvertently get caughton an article of clothing or other object or be accidentally dislodgedor pulled off. Also, the adhesive lip and/or rim design also provide awatertight seal around the electrodes. This seal ensures that electrodeoperation and electrical integrity of the device are maintained whileallowing the wearer the ability to carry on with daily activities. Theslightly protruding, dome shaped electrodes described herein are pressedgently against the skin because of the enhanced adhesion qualities ofthe device.

The electronic memory 122 may be any conventional low powernon-volatile, serial or parallel access memory with sufficient capacityto hold 0.5 Gbytes of data or more depending upon the intended durationof the continuous monitoring period and the intended the fidelity of therecorded signal. Increasing monitoring duration and/or recordingfidelity will increase the amount of storage capacity needed asdescribed in greater detail below. In one embodiment, memory 122 couldalso be a polymer ferroelectric memory such as, for example, the kindsof memory described in US patent application 20070003695, dated Jan. 4,2007 by Alexander Tregub, et al., incorporated herein by reference inits entirety. The size of memory in a continuous cardiac monitorcorresponds, for example, to an amount of memory sufficient to recordcontinuous ECG data from a mammal for the intended monitoring period, orthe expected duration of the monitor remaining affixed to the mammalbased on the type of long term adhesive selected.

Each continuous cardiac monitor may be provided with a uniqueidentifier• such as a serial number or patient information so that whenthe monitor is received for processing as described below, the recordedcontinuous cardiac data is provided to the correct patient or patient'sphysician. Since each monitor may be uniquely identified, a physician oruser initiating continuous monitoring may report the patient name,physician, date and time monitoring initiated into a computer and/orinternet based monitoring system used to analyze continuously recordeddata and generate reports. Specific portions of the data may be obtainedby beginning at time of initiation of monitoring and projecting forward.The clock counter 114 tracks relative time from when the device isplaced on a patient and the initiation of monitoring recorded. Inembodiments having the touch sensors 119 associated with the electrodes105, the touch sensors 119 complete the monitoring circuit andcontinuous recording begins. In another embodiment, time of activationis confirmed by having the user activate the event notation button 130at a designated time on the first day of monitoring. For example, if thepre-determined time is 5 pm, then on the first day of monitoring thepatient will depress the button or activate the event monitor at 5 pm.When the device is later retrieved for processing and evaluation, thedate of initiation is known and, by using the 5 pm event notation on thefirst day, all subsequent readings from 5 pm may be accuratelycorrelated for the remainder of the monitoring period.

Alternatively, the touch sensors 119 may be logically tied with an ANDfunction to the button 130 and input switch 136. In this example, boththe touch sensors 119 and the input switch 136 must provide a signal inorder for the action sequencer 160 to begin recording continuous ECGsignals. Once monitoring begins, the system will have millisecondaccuracy because of the clock generator and the continuous nature of thedata stream. As such, the time of application is known (i.e., recordedat the doctor's office), and the device records linearly for a fixednumber of days afterward.

FIG. 4 illustrates basic physical layout of the components in thecardiac monitor 100. Once properly positioned to detect the ECG signalof a mammal, the ECG signals from the mammal are picked up by theelectrodes 105. As described elsewhere, the touch sensors 119 may beused to ensure that the device is properly attached before initiatingcontinuous monitoring. The analog to digital (A/D) converter 112converts the incoming analog ECG data to digital binary numbers that area raw numeric representation of the ECG signal. The action sequencerstate machine 160 directs the flow of information to either memory 122or to the switch input/data output unit 136. The membrane switch 130 maybe used as an activation or event notation button or switch to increasethe fidelity of the signal being continuously recorded.

Another unique feature of the present invention is the selection and useof electronic components that mirror the simple operations beingperformed by the device. A state machine is a block of custom designed,specific function, sequential control logic, consisting of one flip-flopper binary output state. State machines do not contain centralprocessing units (CPU). One common electronic component that is morepowerful than a state machine is a microcontroller. A microcontrollercontains a simple CPU that incorporates common peripherals on a chip. Atypical microcontroller will incorporate many system level features,such as 110 ports, timers, counters, Pulse Width Modulated outputs,serial ports to support special bus types such as USB, CAN bus, I2C bus,UARTS, watchdog timers, reset circuits, brown out detectors, memoryinterfaces, low voltage detectors, clock circuitry and analog to digitalconverters. Not all microcontrollers will incorporate all thesefeatures, but any CPU that incorporates one or more of the aboveperipherals is generally considered a microcontroller. Another commonelectronic component that is more powerful than both state machines andmicrocontrollers is a microprocessor. A microprocessor is a programmabledigital electronic component that incorporates a more powerful CPU andas well as a variety of complex logic functional elements both withinthe CPU, and surrounding the CPU to support its programmablefunctionality. A microprocessor must be programmed to become functional.Additionally, the CPU also contains an arithmetic logic unit (ALU) whichperforms basic math functions, such as addition, subtraction andmultiplication, and an accumulator to store results. External to the CPUare various control and timing circuits, instruction execution units anddecoders, memory interface and a variety of registers for temporarystorage of data.

The total number of logic gates on various electronic devices is usefulas a gauge to the relative capability of a device to perform complextasks. In general, as the number of logic gates in a device increases,so too increases the ability of that device to perform more complextasks. In general, up to about 10,000 logic gates are provided in statemachines; about 20 k-100 k logic gates is a typical range formicrocontroller devices and about 1-1.5M or more logic gates areprovided in microprocessor devices. For this reason, intermittentcardiac monitoring systems that operate QRS detection and triggeringalgorithms and the like while processing real time ECG data require theprocessing capability of a microprocessor or microcontroller device.

On the other hand, the simple detect-store-offload operations performedby the state machine described herein would likely require only about1000 logic gates. Since so few logic gates are needed to performcontinuously recorded cardiac monitoring, a state machine is the bestfit device when viewed in terms of resource utilization to execute thedefined functions. As such, it is believed that the action sequencer,when adapted to operate as described, will have a resource utilizationratio of between 95% to 100%. The high resource ratio is due to the factthat the state machine offers a logic device tailored exactly to executethe defined functions. It is believed that if a microcontroller deviceor microprocessor device were used to perform the action sequencerfunctions, the resource utilization of those devices would be less than50% and likely between 5% to 15%. From a resource utilizationperspective, microcontroller and microprocessor devices are a poordesign choice. Absent additional processing requirements, one ofordinary skill in the field of computer design would not select amicroprocessor or microcontroller device for the continuous cardiacmonitoring applications of the present invention. The resourceutilization of such devices is so low that such devices would be poordesign choices and would be contrary to accepted engineering resourceutilization guidelines.

FIG. 5 is a schematic diagram of an embodiment of an action sequencercircuit 160. The action sequencer circuit 160 controls the operation ofthe electrical components of the continuous cardiac monitor 100. Thesequencer circuit 160 directs the sequence of action, or steps,necessary for signal acquisition and disposition. Electrodes 105 providecontinuously detected ECG information to the A/D converter 112. Thetouch sensors 119 may be used to ensure that the electrodes are attachedto a surface before allowing monitoring to proceed. In an embodimentusing a 24 bit A/D converter 112, no amplifier circuitry is needed.Typically, 8 bits are used for most bio-signal recording. The range isselected via the 8 to 24 bit selector 161 under the control of theaction sequencer. 8 bit resolution is available throughout the 24 bitrange in any adjacent 8 data lines. Thus, scaling, or amplification isreplaced by selecting the correct range of 8 within the 24 bit span.Additionally, the 24-bit to 8-bit selector serves as a scaler to keepthe signal excursions within the numeric range of the A/D converter, orto provide image scaling for the end user.

FIG. 5 schematically represents three simple timing converter statemachines 162, 164 and 166 included in the action sequencer 160. Theaction sequencer design consists of a load-store and forwardarchitecture with a cut-through mode for real time transmission. In oneembodiment, the action sequencer activation occurs when the touchsensors 119 applied to the electrodes 105 sense that the continuouscardiac monitor 100 has been applied to mammal skin, and, at the same orabout the same time, the membrane button 130 or event notation button131 is pressed for the first time. In one embodiment, both electrodesense and button activation must occur to activate the action sequencer160.

The load-store state machine 162 sequences the data from the A/Dconverter to the memory every chosen clock cycle (i.e., 5 ms). Whenneeded to offload data from memory, a store and forward state machine164 clocks stored data from the memory, and sends it to thecommunications channel 140 where it is transmitted at a much higherspeed than when recorded. A cut through mode state machine 166 allowsthe data to be obtained directly from the A/D converter and transmitted,without use of the memory element, providing a means to transmit data inreal time. A clock circuit 114 also shown. The clock circuit 114generates and sets the timing of operations performing within thecontinuous cardiac monitor 100. The clock generator 114 provides threeclock taps 117 to allow different clocking times to be used in theaction sequencer. Exemplary clock tap values are 1 ms, 5 ms and 10 msbut other values may be used. The clock circuit 114 also ensures data iswritten into the memory 122 at the same rate the A/D converter 112produces them.

The same clock is used to produce similar timing for the dispositionside of the data. When a user requires access to the stored data, aninverse process is initiated (e.g., a push button, or other electricalrequest). Data from the memory is read out, and the data dispositionfunction sends memory data directly to a data port. The data port is anysuitable digital or analog form of direct transmission to a conventionalreading device using a suitable adapter. Examples of suitable adaptersinclude any high speed communications interface that can be adapted to asmall connector inside the device, will be suitable for datatransmission. These communication protocols are can be either serial orparallel, but due to the number of wires in a parallel interface and thedesire to maintain a small footprint design, a serial communicationsprotocol is preferred. These serial protocols can be simple clocked 2 or3 wire interfaces, such as I2C (make the 2 a superscript) by Philips, orSPI by Freescale. More complex alternatives include RS-232, RS-422 oreRS-485 serial protocols, or even higher speed, and higher complexitySERDES (serializer-deserializer) type interfaces. These are the mostpreferred embodiment of the communications channel, as they provided thefastest means of transferring a large amount of data. SERDES basedcommunications include USB 1.1 and USB 2.0, IEEE1394 (known as Firewire)10, 100.1 Gigabit Ethernet.

Turning now to FIG. 5A, flow chart 500 illustrates an exemplary readoperation to store signals received from the electrodes. During a readoperation, the following steps are done one after another by the actionsequencer:

Initiate A/D conversion (step 505)

Acquire data from the A/D according to clock timing (for example, 5milliseconds) (step 510)

Write the data to first or next memory location (step 515)

Increment to next memory location (step 520)

REPEAT to step 505

This process is initiated when the device is placed on the patient.

The sample rate used in embodiments of the present invention is based onthe Nyquist sampling criteria, and the maximum frequency of interest.Typical rates to digitize and sample the data are from approximately 5ms to 10 ms. When a patient perceives an arrhythmia symptom, a eventindicator 131 is activated by squeezing contacts on the device (FIG.13A), pressing a button (FIG. 13B) or in any other suitable manner toregister perception of a symptom. Additionally, the membrane switch 130may be used as an event indicator. When the event indicator isactivated, the sample rate is increased. In one embodiment, the samplerate during a period of high fidelity recording is about half the samplerate during normal continuous recording. In one embodiment, the highfidelity sample rate is from about 2 ms to about 5 ms.

During typical operation, the action sequencer operates at 100 samplesper second with 8 bit resolution. During high fidelity recordingperiods, 16 bits resolution and 200 samples per second may be used. Thehigh fidelity recording mode is activated by the patient pressing,squeezing or otherwise activating an event button 119 or 130 or 131 onthe monitor. The button 119 or 130 may be electrically connected to aninput line of the action sequencer state machine 160. As a normalfunction of the action sequencer is to sample the switch input alongwith the ND converter, the state machine will immediately register andlatch the button pressed state, and commence the specific series of themicrocoded operating sequences that switches the action sequencer torecord in high fidelity. In one embodiment, this process doubles therate of the acquisition of sampling the data by switching to a fastertap of the internal clock, and commences loading 16-bits, or two bytes,instead of one byte from the 24-bits available, and forwards the data tostorage memory 122. One skilled in the art of digital logic design willrecognize that this is a straight forward implementation task withproper design of the state machine microcode.

For an exemplary 30 day continuous monitoring period, recording 100samples per second at 8 bit resolution will require storage capacity ofabout 259.2 megabytes. If the sample rate doubles to about 5 ms over theentire month, about 520 megabytes of storage are needed. Using 10 bitsinstead of 8 bits increases required storage amounts by about 25%. Assuch, an entire month's worth of high fidelity (e.g., 10 bit data/5 mssample rate) continuous ECG data requires less than a gigabyte ofmemory.

The amount of memory required in a continuous cardiac monitor may alsovary depending upon patient perceptions of cardiac events and eventindicator use. A typical event indicator occurrence will increaserecording signal fidelity for 5 minutes, for example. Minimally, on aday when no cardiac events are perceived and the device records at atypical recording rate, a standard daily recording with a 10 ms samplerate at 8 bits, would need consumes 8.64 megabytes of memory per day.

If a patient perceives more events during a day, assume 4 button pressesper day in this example, where 4 high fidelity periods of 5 minutes eachhave been recorded and! the high fidelity sample rate is chosen as 5 mssample rate at 16-bits per sample, then additional memory storage is 200samples/sec×2 bytes/sample×60 sec/min×20 minutes=additional 480K bytesof storage, or about a total of 9 Megabytes per day.

After the monitoring period is completed, the device is removed from themammal and the data stored in memory 122 is retrieved. Data stored inmemory 122 may be retrieved by any suitable technique. For example, theelectronics may be removed from the housing and the communications port140 accessed via an appropriate connector as described above.Alternatively, the housing 152 may be punctured to create an opening inthe vicinity of the port 140. A suitable connector may attach to theport 140 using the opening created in the vicinity of the port 140.

Once the port 140 is accessed, FIG. 5B illustrates the process for anexemplary data disposition or retrieval operation. For the datadisposition operation 550, the sequencer 160 does the following steps,moving from step to step each clock cycle:

Retrieve data from memory location (i.e., first or next location) (step555)

Increment the memory pointer to the next location (step 560)

Write the data to the hardware port (step 565)

REPEAT to step 555

Once initiated, a data disposition operation runs until the last memorylocation is reached, or the last valid data sample is reached, whichevercomes first. While described above as serial operations, the dataacquisition and disposition cycles may be run simultaneously if desired.Once the continuous ECG data is removed from the memory 122, thecontinuous ECG data may be processed using any of a wide variety ofavailable techniques and programs for analyzing ECG data. Many upstreamprocessing algorithms are commonly PC based programs. MoneboTechnologies, Inc. of Austin, Tex. is an example of a company in thebusiness of creating and selling heart health assessment signalprocessing programs. Other companies write their own proprietaryalgorithms, which are included with proprietary monitoring systems.Examples of proprietary processing programs include the Medtronic'sPaceArt Arrhythmia System, Instromedix Gems and HeartMagic PC basedsoftware, Philips Medical DigiTrak Plus Holter monitoring systems andTraceMasterVue ECG management systems.

FIGS. 6A-6D illustrate continuous cardiac monitor embodiments having asingle dedicated electrode pocket 107 with a sealing rim (best seen inFIGS. 6A and 6B) or a tapered thickness flexible lip (best seen in FIGS.6C and 6D). FIGS. 7A-7D below illustrate similar sealing and affixingsurfaces around the use of dedicated electrode pockets 117.

FIGS. 6A and 6B illustrate side and bottom views respectively of acontinuous cardiac monitor 600. The continuous cardiac monitor 600includes the electronic components and performs the functions describedabove with regard to FIGS. 3-5B. The continuous cardiac monitor 600includes a sealing surface 143 and a rim 145, such that when the monitor600 is affixed to a mammal, a single dedicated electrode pocket 107 isformed. The single electrode pocket 107 is used to form the watertightchamber that will contain the electrodes during the monitoring period.Two electrodes 105 are shown, but more electrodes could be provideddepending upon the specific monitoring to be performed. As best seen inFIG. 6B, the adhesive 148 is coextensive with the surface 143. In use,when the adhesive 148 is affixed to the mammal, the rim 145 extendingfrom the surface of the housing forms a watertight chamber, here theelectrode pocket 107, around and including the two electrodes 105. FIG.6A also illustrates that in use a single watertight enclosure 107 wouldbe bounded by the interior of the chamber 107 and the skin of themammal.

FIGS. 6C and 6D illustrate side and bottom views respectively of acontinuous cardiac monitor 650. The continuous cardiac monitor 650 issimilar in construction to the monitor 600 with the addition of theflexible seal 150 that extends beyond the central portion of the housing133 into a tapered perimeter. The flexible seal 150 increases the amountof surface area available for affixing and sealing the monitor to themammal during the monitoring period. Monitor 650 includes a sealingsurface 143 that when the monitor 650 is affixed to a mammal, adedicated electrode pocket 107 is formed, as described above in FIG. 6A.As best seen in FIG. 6D, the adhesive 148 is coextensive with thesurface 143. In use, when the adhesive 148 is affixed to the mammal, thesurface 143 forms a watertight seal that forms the dedicated electrodepocket 107, around the two electrodes 105. FIG. 6D also illustrates thatin use watertight enclosures 107 are provided around both electrodes105.

FIG. 6C also illustrates an alternative electrode embodiment. Onechallenge in long term monitoring is that mammal skin cannot easilytolerate long term application of conventional electrodes, typicallycomprising chemicals such as sliver chloride embedded in an active,conductive electrolyte. These types of conventional electrodes alsodeteriorate in performance over time as the electrolyte dries out orbecomes contaminated. Although it is contemplated that more hypoallergenic electrodes and companion electrolytes may be developed, andcould be used effectively in the current device, one embodiment of thepresent invention uses dry skin, capacitive or non-reactive ohmiccontact electrodes. In one embodiment, electrodes 105 may be adapted forlong term applications by constructing the electrodes from stainlesssteel, or Tantalum. Additionally, a uniformly thin film coatingcomprising Tantalum Pentoxide (Ta.sub.2O.sub.5), which is an inert thinfilm of glass may be used. This thin coating 111 is illustrated in FIG.6C on the rounded surface 106 of electrodes 105. The drawing is not toscale and the thickness of the coating is exaggerated for purposes ofillustrating its location. The thin coating may be applied byconventional coating means. Alternatively, the so called super coatingprocess developed by the Sanford Process Corporation may be used. Thesuper coating process provides a hard coating of penetrating anodizationof aluminum. With either process, DC resistances of more than 1 G ohm isachieved, and the capacitor formed ranges from 0.01 microfarad to 0.1microfarad. Although ranges can vary, the capacitance of the electrodesin a monitor should be matched in value for best common mode rejection.

There is another physical differentiating characteristic in theelectrode designs used in the present invention. Since the electrodesonly minimally protrude beyond the surface of the housing they are alsounlikely to cause skin breakdown since they are not exerting significantenough pressure on the skin. Further, as there are no significant sharpedges on these electrodes and as the contact area with the skin isspread over the electrode surface, skin breakdown is unlikely sincethere are no focal or sharp pressure points. There are no sharp squareedges as found in common intermittent monitors. Sharp edges may betolerated for short monitoring periods but are not suited to long termcontinuous monitoring applications. In contrast, electrodes 105 includea softer rounded edge 106 that helps to mitigate or minimize irritationduring long term skin contact. As best seen in FIG. 6C, the surface seenin profile has a gentle curve 106, typically with a smooth radius thatis free from sharp edges. The dome shape spans the top of the electrode105 in the region of skin contact to provide good signal contact withoutedge irritation while reducing tribo-electric noise generated by motionof skin in contact with sharp corners (as is common in conventionalmonitors).

FIG. 6C also illustrates an LED indicator 610 useful to show properoperation of the monitor as the monitoring period progresses. In thisembodiment, low power, multicolored light emitting diodes 610 areprovided as state machine status indicators. When the device is firstmanufactured and in storage, the LED is inactive. Once applied and themembrane switch 130 is pressed for the first time, the LED indicatoractivates when the ECG of the mammal wearing the device is detected. TheLED indicator may produce a green burst flash (or other suitable color,such as blue) once every 5 seconds, or at some other interval. In oneembodiment, a longer flash interval period is used to preserve batteryenergy. Intervals may be up to about 1 minute apart. The LED may also beconfigured to provide a continuous indication as long as the ECG of themammal is detected. A continuous indication in this context refers to anindication that is persistent during the monitoring period. As such, aflashing indicator could be considered a continuous indication if theflashing remained during monitoring. A continuously illuminated LED andthe like would also be suitable continuous indications.

If one or both of the electrode touch sensors detect a higher than 1Mohm impedance level, the flashing LED changes to yellow (or othersuitable standard color), indicating a bad skin contact, and a poorquality recording would result, so the patch needs to be changed. Thismay occur on initial application, or anytime during the time the deviceis worn.

Once the memory is full and the device can longer record, The flashingLED changes to red (or other suitable designated color), indicating tothe patient that the patch must be sent or carried back to a locationdesignated by the physician, so that the recorded data may be retrieved.Other colors may be beneficially used for other key indicators, such as“one day left to record”. Once removed, the LED stops flashing toconserve power.

FIG. 6D also illustrates various dimensions useful in describingcontinuous cardiac monitors. While described in terms of the embodimentof FIG. 6D, the design parameters and general dimensions that follow areapplicable generally to continuous cardiac monitor embodiments. Severalgeneral device dimensions are illustrated in FIG. 6D. Device dimensionsvary in sizes, depending on the size of the mammal. Width dimension Amay effectively vary from 2 cm to 6 cm with 4 cm+/−2 being a suitablerange. Similarly, the overall length dimension B may vary from 5 cm to10 cm, with 7 cm nominal. The dimension C indicates electrode spacing.The spacing and placement of the electrodes is critical for two reasons.First, the minimum separation is necessary to pick up an ECGdifferential signal without outside amplification. This separationvaries by mammal, but always must meet a minimum separation of 5 cm forthe smaller mammals, to 6 cm for humans, and larger mammals. Second, theelectrodes must be well inside and away from the edges of the adhesivepatch, to maintain top performance and prevent outside contamination.Embodiments of the present invention provide rims, lips, taperedsurfaces alone or in various combinations to ensure the desiredelectrode operating environment is maintained during the monitoringperiod. In one embodiment, the dimension C varies linearly andproportionally with the overall length of the patch. In one embodiment,the ratio of B to C would be about 1.25. Additionally, designs may bealtered to provide an additional design parameter that the electrodemust be at least 8 mm from any edge of the monitor. This designparameter ensures that at least an 8 mm sealing edge is provided by eachelectrode. Embodiments of the rims and sealing lips described herein maybe adapted to meet this design feature. Additional dimensionalinformation is described below with regard to FIGS. 8A-8C. Moreover, theheight, or thickness of the patch is important so that the upper surfaceof the monitor when affixed to the skin minimizes obstruction ofclothing, harnesses or activities. In one embodiment, the range of Ddimension values range from 0.5 cm to 1.5 cm.

FIGS. 7A-7D illustrate continuous cardiac monitor embodiments havingdedicated electrode pockets 117. The continuous cardiac monitorsdescribed in FIGS. 7A-7D include the electronic components and performthe functions described above with regard to FIGS. 3-5B. FIGS. 7A and 7Billustrate side and bottom views respectively of a continuous cardiacmonitor 700. The continuous cardiac monitor 700 includes a sealingsurface 143 and a rim 745, such that when the monitor 700 is affixed toa mammal, dedicated electrode pockets 117 are formed. As best seen inFIG. 7B, the adhesive 148 is coextensive with the surface 143. In use,when the adhesive 148 is affixed to the mammal, the rim 745 forms awatertight chamber; here the dedicated electrode pockets 117, around thetwo electrodes 105. FIG. 7A also illustrates that in use separatewatertight enclosures 117 are provided around each electrode 105.

FIGS. 7C and 7D illustrate side and bottom views respectively of acontinuous cardiac monitor 750. The continuous cardiac monitor 750 issimilar in construction to the monitor 700 with the addition of theflexible seal ISO that extends beyond the central portion of the housing133 into a tapered perimeter. The flexible seal ISO increases the amountof surface area available for affixing and sealing the monitor to themammal during the monitoring period, similar to FIG. 6C. Monitor 750includes a sealing surface 143 that when the monitor 750 is affixed to amammal, dedicated electrode pockets 117 are formed. As best seen in FIG.7D, the adhesive 148 is coextensive with the surface 143. In use, whenthe adhesive 148 is affixed to the mammal, the surface 143 forms awatertight seal that forms the dedicated electrode pockets 117, aroundthe two electrodes 105. FIG. 7D also illustrates that in use separatewatertight enclosures 117 are provided around each electrode 105.

FIGS. 8A, 8B and 8C are, respectively, top, bottom and side views of acontinuous cardiac monitor 800 according to an alternative embodiment ofthe present invention. The continuous cardiac monitor described in FIGS.8A-8C includes the electronic components and performs the functionsdescribed above with regard to FIGS. 3-5B. The cardiac monitor 800includes two activation or event notation buttons or switches 130 withinan elongated housing 152. The dog bone shaped housing extends the length(indicated as b in FIG. 8A) to provide greater variability of electrodespacing (indicated as c in FIG. 8B) while still providing an adequatelysized surface 143 to ensure a good seal and long term adhesion. Theelongate axis b may provide alternative configurations adapted formonitoring small animals such as dogs and large mammals such as horseswhere the curvature of the rib cage or other attachment point is subjectto wide anatomical variation. Moreover, such designs may be suited tomonitoring humans but with the monitor 800 configured to wrap partiallyaround the torso rather than being placed directly over the heart. Theindicated a dimension in FIG. 8A may be about 1 inch. The indicated bdimension in FIG. 8A may be about 2-3 inches. The indicated c dimensionin FIG. 8B may be from about 1.5 to 2.5 inches. The indicated ddimension in FIG. 8C may be about or less than 0.5 inches.

FIG. 9 illustrates device 800 movement (in phantom) during attachment ofthe monitor to the chest 16. Once a good signal is received (indicatedusing the indicators described herein for example) the monitor isaffixed to the mammal.

FIG. 10 illustrates a continuous cardiac monitor 900 according to analternative embodiment of the present invention. The continuous cardiacmonitor illustrated in FIG. 10 includes the electronic components andperforms the functions described above with regard to FIGS. 3-5B. Thehousing 152 in this embodiment includes a plurality of arms 910. Eacharm includes a surface 143, an adhesive 148 and an electrode pocket. Theelectrode pocket may be of any of the types described herein such assingle pocket 107 or individual electrode pockets 109. More or fewerarms, the length of the arms and the dimensions L and W may be adjusteddepending upon a number of factors, such as, for example, the positionof the monitor 900 on the mammal and the size of the mammal. Largerdimensions L and W may be used to adapt the monitor for use on horsesor, alternatively, if the monitor is affixed to the back rather than thechest of a human.

FIG. 11 illustrates a circular continuous cardiac monitor 1100 accordingto an alternative embodiment of the present invention. The continuouscardiac monitor illustrated in FIG. 11 includes the electroniccomponents and performs the functions described above with regard toFIGS. 3-5B. The housing 152 in this embodiment is generally circular andincludes an annular shaped surface 143 having adhesive 148 thereon. Thesingle electrode pocket 107 in this embodiment includes 3 electrodes105. Alternatively, the single electrode pocket 107 may be modified intothe dedicated form of electrode pocket 117 described above. Thedimensions of this embodiment—having more or fewer electrodes—may bewell suited to continuous cardiac monitoring applications for largemammals such as horses.

FIG. 12A illustrates a continuous cardiac monitor 1150 according to analternative embodiment of the present invention. The continuous cardiacmonitor illustrated in FIG. 12A includes the electronic components andperforms the functions described above with regard to FIGS. 3-5B. Thehousing 152 in this embodiment is generally rectangular and includes arim 150 with an adhesive 148 as described above. The single electrodepocket 107 in this embodiment includes 4 electrodes 105. Alternatively,the single electrode pocket 107 may be modified into the dedicated formof electrode pocket 117 described above. The dimensions of thisembodiment—having more or fewer electrodes—may be well suited tocontinuous cardiac monitoring applications for large mammals such ashorses. FIG. 12B illustrates an embodiment of the cardiac monitor 1150in position on the chest 16 to detect cardiac signals.

FIGS. 13A and 13B illustrate alternative activation or event notationbutton or switch embodiments. The continuous cardiac monitorsillustrated in FIGS. 13A and 13B include the electronic components andperforms the functions described above with regard to FIGS. 3-5B. Themembrane switch 130 is one form of an activation or event notationbutton or switch. An activation or event notation button or switch isany device used by the mammal wearing the: device to indicate theperception of symptoms. An activation or event notation button or switchmay be formed in the housing 152 in a manner such that the eventnotation capability remains accessible for activation while the adhesiveis affixed to the mammal. Activation or event notation buttons orswitches 130 and 131 are accessible when the device is affixed to themammal. Activation or event notation button or switch 131 illustrated inFIG. 13A is activated by squeezing the tabs on the button together. Thisdesign requires additional action by the user to register the event andmay be useful to minimize false event registration. Similarly, themembrane switch 130 described above is below the surface of the housingand requires depressing of the surrounding housing to register an event.The activation or event notation button or switch 131 illustrated inFIG. 13B is similar to the membrane switch 130 except that it positionedbelow the surface of the housing. As described above, actuation of anactivation or event notation button or switch increases the fidelity ofthe cardiac information stored in the electronic memory. Activation orevent notation button or switch activation is stored in the electronicmemory with contemporaneous cardiac information. In this way, thecardiac data contemporaneous to the patient's perceived symptoms can beanalyzed using the methods described below.

FIG. 14 illustrates a cardiac monitor 1400 having a circular centralportion housing 152. As with previous embodiments, the electroniccomponents are contained inside the housing and the illustratedcontinuous cardiac monitor in FIG. 14 includes the electronic:components and performs the functions described above with regard toFIGS. 3-5B. In this embodiment, the flexible sealing lip 150 includespores to enhance long term patient comfort. Similar to how a porousbandage allows air to aid in healing, it is believed that adding poresto flexible lip will enhance breath ability of the skin and lead togreater patient comfort during long term continuous monitoring.Moreover, this or other embodiments of the flexible lip 150, housing 152or other components have be altered to include pleasing features such ascartoon characters, symbols from athletic teams, mottos, slogans ordecorative designs to enhance the visual appeal of the device.Additionally or alternatively, all or a portion of the device may becolored or tinted to either increase the visibility of the device on themammal (i.e., add a brightly colored pigment to the housing) or decreasethe visibility of the device on the mammal (i.e., modify the outwardappearance of the device to closely match the appearance of the mammalwhere the device is to be mounted). Modifications to the outwardappearance of the device to closely match the appearance of the mammalwhere the device is to be mounted include such things as adding pigmentto match the mammal skin tone or adding fur or hair to match the fur orhair on a horse, dog or other animal under going continuous monitoring.While described in the context of the embodiment of FIG. 14, thesefeatures are not so limited and may be applied to other embodiments ofthe invention.

Embodiments of the continuous cardiac monitor described herein provide arobust set of patient cardiac data for processing and evaluation. Theavailability of this data now enables physicians and health careproviders with additional methods to evaluate the condition of apatient. Additionally, this new type of cardiac data leads to newprocesses of maintaining and controlling the flow and availability ofthe data. These methods will be described with reference to the flowcharts in FIGS. 15-19.

FIG. 15 illustrates a method of obtaining and evaluating continuouscardiac data. First, at step 1505 a box of patches or continuous cardiacmonitors is provided to a health care provider at a hospital, clinic orother treatment center. Next, at step 1510, a patient with suspectedarrhythmia sees the health care provider. A continuous cardiacmonitoring patch is placed on the patient. The physician or assistantlogs the application of the patch to the patient, noting the uniquepatch identification as well as the date and time of initiation ofmonitoring. Logging initiation of monitoring may be accomplished using asoftware tracking system in the physician's office, by accessing adatabase via the Internet or by any other means to document initiationof monitoring. Additionally or alternatively, the patient may alsofollow a pre-set initiation ritual which includes placing a known markerinto the data stream at a specific time after the initiation ofmonitoring. For example, at 5 pm on the first day of monitoring, thepatent may activate the event registration button to provide a way tosynchronize the continuous data recording more precisely to the start ofdata acquisition.

Next, during the monitoring period, the patch records all cardiac:rhythm continuously without interruption (step 1520). Additionally, thepatient may note onset of symptoms by pressing the event registrationbutton or switch. Next, at step 1530, at the conclusion of themonitoring period, data is downloaded from the patch at the physician'soffice, a clinic or other site configured to receive and download storedcontinuous cardiac data. Optionally, the patient may provide the patchto a processing center, or download and transfer the stored data himselfor herself.

Next, at step 1540, continuous cardiac data is downloaded from the patchor received if the data is sent. Recorded patch data is linked to storedpatient information. Multiple different algorithms, processingtechniques and methodologies may be used to analyze the continuouscardiac data. Based on this analysis, a report is generated. Next, atthe hospital or clinic, the physician or health care provider reviewsand interprets the report at his or her convenience (step 1550).Importantly, because all of data from the entire reporting period isavailable, the physician may also access the continuous data to aid inthe treatment of a patient. One advantage of having continuous cardiacdata—rather than filtered data as in intermittent cardiac rhythmmonitors—is that the data may be used to assure a patient that he or shedoes not have any arrhythmia. A physician reviewing intermittent cardiacrhythm data would need to provide a caveat that the monitor did notdetect any arrhythmia. In contrast, a physician who evaluates continuouscardiac data may base his opinion on a review of all cardiac data. Theimportant difference is that with continuous cardiac data thephysician—not an algorithm—determines whether a heart beat is abnormal.

FIG. 16 illustrates a comprehensive method 1600 of how the availabilityof continuous cardiac monitoring devices will enable new methods oftreating patients and evaluation cardiac data. Once a patient perceivessymptoms of abnormal cardiac activity (step 1602), there are severalways a continuous cardiac monitoring patch may be placed on a patient(step 1630).

The patient may obtain one at a pharmacy and apply (step 1604). A patchmay be available from any of a wide variety of locations and undervarious arrangements. Obtaining a patch from a pharmacy is merely forpurposes of illustration.

The patient may call his primary care provider (PCP) at step 1608 andthen find that the symptoms were not serious and that he is OK (step1610). Alternatively, the call to the PCP may result in the patientgoing to the emergency room (step 1612) and being admitted to thehospital (1614). The patient may be discharged (step 1615) and provideda patch to wear (1630) for continuous monitoring following emergencyroom discharge. Alternatively, admission to the hospital (step 1614) mayresult in a cardiologist referring the patient to an electrophysiologist(EP) (step 1622). The EP may place the patch on the patient (step 1624)an initiate continuous monitoring.

Another result of the patient call to the PCP (step 1608) is that thePCP will mail or otherwise provide a patch to the patient withinstructions to affix the patch and initiate continuous monitoring (step1618). Another alternative is that the patient will have an office visitwith the PCP (step 1616). The visit may result in a patch being mailedto the patient (step 1618) or being applied to the patient by the PCP(step 1628) in the PCP office. Another option is that the PCP will referthe patient to a cardiologist (step 1620) who applies the patch to thepatient (step 1626).

At the conclusion of any of the above treatment scenarios, there is apatch on the patient (step 1630).

Once the patch is associated with a specific patient, a number ofvarious steps may be undertaken depending upon the specificcircumstances of the patient and the desired treatment plan desired by aphysician. In addition to the steps detailed below, the patch mayoperate as described above with regard to embodiments of the cardiacmonitor 100 to record all cardiac activity during a monitoring period.The patch may be used to record everything without any assessment (step1632) during the monitoring period. Alternatively, the patient may callhis physician if symptoms are perceived. General parameters are used totrigger recording (passive) (step 1634). Events or symptoms felt ornoted by a patient may also be recorded (step 1636) through activationof an event registration button. This triggering does not impede oralter the storage of the continuously recorded cardiac data, but ratheradds a notation to alert a physician analyzing the data subsequentlyafter monitoring has been completed that the patient felt an event orsymptom at this point of the continuous data recording. A patient may beprovided with multiple kinds of patches (step 1638). The patient may beprovided with a standard patch (same hardware and construction) thatundergoes software programming in the physician's office (step 1640). Atthe end of the monitoring period, continuous cardiac data has beencollected (1642). Detecting an ECG signal of a mammal and storing allthe detected ECG signals are performed without identifying ECG events inthe information collected during the monitoring period.

Since the monitoring period is a pre-determined period, notification ofthe conclusion of monitoring may be performed in any number of ways. Anotification may be provided to the patient to mail the patch in forprocessing (step 1644). The patient may receive a call from a nurse orother health care provider (step 1646). The patient may simply go to apre-arranged appointment where the patch is removed (step 1648). Anautomated calling program may notify the patient that monitoring hasended (step 1650). The patient may receive a notice in the mail with areminder of the monitoring end point and also include instructions onhow to return the device (step 1652). The patient may be notified of theconclusion of monitoring via a wireless messaging system (1654). Anaudible alarm or beep may be emitted to indicate the end of monitoring(step 1656). Optionally, the notification may be from a configuration oflights on the monitor as described above with regard to FIG. 6C.

Once monitoring has ended, the device may be returned for processing inany of a number of ways. The device may returned to the hospital whichwill then forward the device and/or data on for processing (step 1658).The device may be picked up from the patient (step 1650). The patientmay also mail the patch themselves to a processing center or health careprovider (step 1662). The patch may include a design that allows it tounfold into a larger shape to make handling easier (step 1664).Optionally, the patch may be returned using an envelope (step 1666), byaffixing it to a postcard (step 1668), by using a return mailer from amonitoring company or health care provider (step 1670) or by using acard in a wallet (step 1672). Once the patch has been removed from thepatient, it is provided to, delivered to or made available to themonitoring company using any of the techniques above (step 1674). Afterthe monitoring company has the patch, it will be able to retrieve storedinformation related to substantially all detected cardiac signals fromthe monitor. Next, the data is analyzed or processed (step 1676). Thisanalyzing step is performed after the ECG monitor is removed from themammal. The retrieved information from the patch is analyzed to identifyECG events. Additionally, the algorithms may be used to process storedinformation to determine the presence of an arrhythmia. Additionally,there is also the step of processing information stored on the deviceusing more than one algorithm to determine the presence of anarrhythmia.

After data processing, a generic report (step 1680) or a specific reportmay be generated. Additionally or alternatively, the output of dataprocessing may be made available through a website (1678) where a usermay select other techniques to process and evaluate the collected data.As a result of reviewing the report or using the website, or in anyevent, the monitoring company may provide additional details on request(step 1682).

At the conclusion of the monitoring process, a patient may return to hisPCP for further evaluation and diagnosis (step 1684). As a result of theevaluation of the monitoring process, the PCP may refer the patient to acardiologist (step 1686), apply a new patch to the patient and initiatean additional monitoring session (step 1688) or determine that thepatient is OK and requires no further treatment or monitoring (step1690).

Turning now to FIG. 17, another alternative cardiac data processingmethod 1700 that is enabled because of the availability of continuouscardiac data provided by embodiments of the continuous cardiac monitor100 is shown.

A patient has symptoms that could be due to an arrhythmia (step 1705).Next, the patient sees a health care provider or seeks medical attention(step 1710). The health care provider puts a patch on the patient (step1715) and initiates the monitoring period. All cardiac data iscontinuously recorded and stored without any interruption for at least 7days (step 1720). During the monitoring period, if a symptom is felt,the event registration button is pressed by patient (step 1722).

The patch is removed after a specified period of time or if the patientis instructed to or wants to remove the patch (step 1725).

Next, the patch may be taken to the health care provider (step 1730) orcan be sent to the processing center by patient (step 1735). If thepatch is taken back to the health care provider, the data may bedownloaded by the health care provider (step 1740). The patch can alsobe sent to the processing center by the health care provider (step 1745)or the patient (step 1735), and the data is downloaded at the processingcenter (step 1750).

Whether the data is sent to the processing center by the health careprovider (step 1755) or downloaded by the processing center (step 1750),the continuous cardiac data obtained during the monitoring period isanalyzed using multiple algorithms for increased accuracy (step 1760).Thereafter, a comprehensive report of findings is created (step 1765).An electronic version of the report may be sent to a website for review(step 1770). Optionally, a paper version of report can be sent to ahealth care provider for review (step 1775). Regardless of how theresults of the comprehensive findings are provided, more details of thefindings are available using the website (step 1780).

Additional other methods are enabled by the embodiments of thecontinuous cardiac monitors described herein. FIG. 18 illustrates onemethod of storing all or substantially all of the cardiac data of amammal as illustrated by method 1800. In this method of obtainingcardiac information from a mammal, the first step is attaching aself-contained, wearable, portable cardiac monitor to the mammal tocreate a chamber containing electrodes used to detect cardiac signalsfrom the mammal (step 1810). Next, using the self-contained, wearable,portable cardiac monitor, continuously detect without analyzing thecardiac signals from the mammal for at least 24 hours (step 1820).Finally, store information related to substantially all detected cardiacsignals in the cardiac monitor (step 1830). In one aspect of thismethod, the self-contained, wearable, portable cardiac monitorcomprises: a plurality of electrodes, a power source and memorycontained within a watertight housing. Alternatively, the cardiacmonitor may provide a mammal perceivable indication that the cardiacmonitor is operating. In another aspect of operation, the cardiacmonitor provides an indication that the cardiac monitor is operatingafter the attaching step. The operation of the cardiac monitor based onthis indication shows that continuous cardiac data is being collected bythe cardiac monitor.

The steps detailed in method 1800 may also be modified in certainembodiments. For example, the detecting and storing steps are performedwithout identifying cardiac events in the information related tosubstantially all detected cardiac signals. In another alternative, thedetecting and storing steps are performed without transferringinformation between the housing and a device not attached to the mammal.

In another alternative, the detecting and storing steps are performedwithout transferring information between the housing and a device notcontained within the housing. The steps of the method may be performedin a certain order, as discussed above. Optionally, for example, theorder may be changed or additional steps added. The providing step isperformed after the attaching step, for example. In another example, theproviding step is performed after the storing step. In another example,the providing step is continuously performed during a continuouslydetecting step. Optionally, the attaching step includes placing theelectrodes on the mammal and sealing the electrodes between the housingand the mammal using an adhesive on a rim of the housing that surroundsthe electrodes.

Other steps may be taken in addition to those detailed in method 1800.One step that may be added includes retrieving stored informationrelated to substantially all detected cardiac signals from the monitor.Furthermore, the retrieved information to identify cardiac events may beanalyzed. Optionally, the analyzing step is performed after the cardiacmonitor is removed from the mammal. In another alternative, the cardiacmonitor is removed from the mammal before the retrieving step. Inanother alternative, information from the storing step is processed toevaluate the presence of an arrhythmia during a time interval indicatedby the mammal.

The method 1800 may also be modified to include different techniques forprocessing continuous cardiac data. For example, information from thestoring step may be processed to determine the presence of anarrhythmia. Optionally, information from the storing step is processedusing more than one algorithm to determine the presence of anarrhythmia. Alternatively, information from the storing step isprocessed to evaluate the presence of an arrhythmia during a selectedtime interval. In one embodiment, the information from the storing stepis processed during the same selected time interval on more than oneday.

The availability of self-contained, wearable, portable cardiac monitorssuch as those embodiments described above, enable new processes ofanalyzing continuously collected cardiac data. One exemplary process1900 of collecting and analyzing cardiac data is illustrated in FIG. 19.The first step in this process of analyzing cardiac information is tocollect a plurality of self-contained, wearable, portable cardiacmonitors, each of the cardiac monitors electronically storing at least24 hours of continuously detected and unanalyzed cardiac signals from amammal (step 1910). This step is possible using any of the embodimentsof the continuous cardiac monitor 100 described above. The next step,step 1920, involves retrieving cardiac information stored in each of theplurality of self-contained portable cardiac monitors. Finally, at step1930, retrieved cardiac information is forwarded. Forwarded in thecontext of this application includes physically forwarded such as when ahardcopy of the data is provided to a user. Forwarding also includesactivity that purposely provides information to a user such as in aletter, an e-mail or other form of communication to a user. Forwardingalso includes the act of making the retrieved data available for accessby a user. In this context, retrieved data would be considered forwardedwhen the data is available for access by a user on a website, dedicatedprogram or by other means accessible to the user by user access.

The specific details of the method 1900 may be modified. For example, inone alternative, the mammal specific information in at least one of theplurality of self-contained, wearable, portable cardiac monitorsincludes substantially all of the cardiac information from a mammal forat least 7 days. In another alternative, the cardiac information in theforwarding step includes substantially all of the cardiac informationfrom a mammal for at least 7 days. In yet another alternative, theforwarding step includes providing mammal specific cardiac informationto a physician identified in the collecting step.

The specific steps of the method 1900 may also be modified. For example,the method 1900 may include the step of sending the collectedself-contained portable cardiac monitors to a processing center beforethe retrieving step. In one specific embodiment, the forwarding stepincludes the step of electronically sending retrieved cardiacinformation to a processing center. In another alternative, the step ofremoving a self contained portable cardiac monitor from a mammal isperformed before the collecting step.

The process 1900 may also be modified to include a variety ofalternative processing steps. In one alternative, the retrieved cardiacinformation may be analyzed to identify cardiac events or parameters.Optionally, the analyzing step is done after the forwarding step. Inanother step, information from the forwarding step is processed todetermine the presence of an arrhythmia. In another alternative, theinformation from the forwarding step may be processed using more thanone algorithm to determine the presence of an arrhythmia. In anotheradditional step, the information from the forwarding step may beprocessed to evaluate the presence of an arrhythmia during a selectedtime interval. The selected time interval may be during the sameselected time interval on more than one day or a time interval indicatedby the mammal. In another step of the process, information from theforwarding step may be processed to determine the presence of anarrhythmia.

The method 1900 may also be modified in other ways, such as to provide auser access to data collected by the continuous cardiac monitor. Oneadditional step includes providing a user access to information from theretrieving step or the forwarding step so that the user may process theprovided information using more than one algorithm to determine thepresence of an arrhythmia. Alternatively, another additional stepprovides a user access to information from the retrieving step or theforwarding step so that the user may process the provided information toevaluate the presence of an arrhythmia during a time interval indicatedby the mammal. In yet another step, a user is provided access toinformation from the retrieving step or the forwarding step so that theuser may process the provided information to evaluate the presence of anarrhythmia during a selected time interval. In one alternative, theprovided information is processed during the same selected time intervalon more than one day.

While numerous embodiments of the present invention have been shown anddescribed herein, one of ordinary skill in the art will appreciate thatsuch embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will now occur to those skilledin the art without departing from the invention. It should be understoodthat various alternatives to these embodiments of the inventiondescribed herein may be employed in practicing the invention. It isintended at the following claims defined the scope of the invention andit methods and structures within the scope of these claims and theirequivalents be covered thereby.

What is claimed is:
 1. A method of obtaining continuous cardiac rhythminformation from a mammal, the method comprising: providing aself-contained, wearable, portable cardiac monitor enclosed in awatertight housing configured for continuous attachment to the mammalfor at least 7 days, wherein the cardiac monitor includes at least twoelectrodes used to detect the continuous cardiac rhythm information fromthe mammal and an adhesive configured for continuous attachment to themammal for the at least 7 days, wherein a distance between a center ofone of the electrodes and a center of another of the electrodes is atleast about 5 cm; detecting, using the at least two electrodes, thecontinuous cardiac rhythm information from the mammal continuously forthe at least 7 days, including both normal cardiac rhythm informationand abnormal cardiac rhythm information, and operating an actionsequencer having no central processing unit for rhythm analysis tostore, for the at least 7 days, all of the continuous cardiac rhythminformation detected during the at least 7 days, including the normalcardiac rhythm information and the abnormal cardiac rhythm information,without performing a rhythm analysis of the continuous cardiac rhythminformation, wherein the watertight housing of the cardiac monitorallows the mammal to bathe and otherwise expose the cardiac monitor towater without requiring removal of the monitor during the at least 7days and thus provides for the detecting and storing of continuouscardiac rhythm information by the monitor throughout the at least 7days, thereby allowing for a more complete assessment of all normal andabnormal cardiac rhythms and their total durations during the at least 7days, based on continuous, uninterrupted cardiac rhythm informationstored by the monitor.
 2. The method according to claim 1, wherein theat least two electrodes, a power source and the memory of theself-contained, wearable, portable cardiac monitor are contained withinthe watertight housing.
 3. The method according to claim 2, wherein theadhesive on the housing is configured to create separate, watertightchambers around each electrode when the housing is attached to themammal.
 4. The method according to claim 1, further comprisingindicating that the cardiac monitor is operating, using an indicator onthe cardiac monitor.
 5. The method according to claim 4, wherein theindicating is performed after the cardiac monitor is attached to themammal.
 6. The method according to claim 4, wherein the indicating isperformed during the operating step.
 7. The method according to claim 1,further comprising retrieving all the stored cardiac rhythm informationfrom the monitor.
 8. The method according to claim 7, further comprisingremoving the cardiac monitor from the mammal before the retrieving step.9. The method according to claim 7, further comprising analyzing theretrieved cardiac rhythm information to identify cardiac events.
 10. Themethod according to claim 9 wherein the analyzing step is performedafter the cardiac monitor is removed from the mammal.
 11. The methodaccording to claim 1, wherein the operating step is performed withouttransferring information between the housing and a device not attachedto the mammal.
 12. The method according to claim 1, wherein theoperating step is performed without transferring information between thehousing and a device not contained within the housing.
 13. The methodaccording to claim 1, further comprising processing the storedcontinuous cardiac rhythm information after the operating step todetermine the presence of an arrhythmia.
 14. The method according toclaim 13, wherein processing the stored continuous cardiac rhythminformation comprises using more than one algorithm to determine thepresence of the arrhythmia.
 15. The method according to claim 13,wherein processing the stored continuous cardiac rhythm informationcomprises determining the presence of the arrhythmia during a selectedtime interval.
 16. The method according to claim 15, wherein thecontinuous cardiac rhythm information from the operating step isprocessed during the same selected time interval on more than one day.17. The method according to claim 13, wherein processing the storedcontinuous cardiac rhythm information comprises determining the presenceof the arrhythmia during a time interval indicated by the mammal duringthe detecting step.
 18. The method according to claim 9 wherein theanalyzing step is performed by a processor not contained within thehousing.
 19. The method according to claim 1, wherein the same at leasttwo electrodes are used while performing the operating step for the atleast 7 days.
 20. The method according to claim 3, wherein the housingcomprises separate rims surrounding each of the two electrodes, andwherein the rims are configured to create the separate watertightchambers around the electrodes.